Obraik:
I understand, it's because the Japanese government pushed heavily for hydrogen and so the Japanese companies followed along and put most of their eggs in that basket.
Several reasons really -
Japan has/had a lot of Nuclear power to generate hydrogen - thats not really true any longer
Car manufacturing is a massive part of Japans jobs/industry - fuel cells keep a lot of similar manufacturing going
It seemed like a decent bet back in the 80s and 90s but it just hasnt panned out whilst battery tech has improved rapidly